Elastic body, bump stop, electromagnetic induction device, power generation system, detection device, and production method for elastic body
An elastic body of this disclosure contains magnetized magnetic powder dispersed in an elastic member, and generates an induced current in a circuit by undergoing an elastic deformation to cause a change in magnetic flux density. The elastic member is an elastomeric foam.
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The present disclosure relates to an elastic body and a production method thereof, a bump stop, and also to an electromagnetic induction device that generates an induced current in a circuit, a power generation system, and a detection device.
(2) Description of Related ArtAn electromagnetic induction device that generates an induced current in a circuit by vibrating a ferrite magnet is known before (see, for example, Japanese Registered Utility Model No. 3051758 paragraphs [0020] to [0022] and [0026],
However, the problem with ferrite magnets was that they were readily breakable because of the brittle and fracturable nature.
An elastic body according to the present disclosure is made of an elastic member containing a magnetized magnetic powder dispersed therein and generates an induced current in a circuit by undergoing elastic deformation to cause a change in magnetic flux density, the elastic member being an elastomeric foam.
As illustrated in
The elastomeric foam 21 may be a polyurethane elastomeric foam, a rubber foam, or a thermoplastic resin foam such as a polyolefin-based resin foam. The elastomeric foam 21 should preferably have a continuous air bubble structure or a semicontinuous air bubble structure from the points of view of formability and elastic deformability. The elastomeric foam 21 should preferably at least include a part that has a continuous air bubble structure so that contraction (known as shrinkage) of the elastomeric foam 21 after the forming can be inhibited. Moreover, the elastomeric foam 21 should preferably have an expansion ratio of 1.4 to 6 folds, more preferably 1.7 to 5 folds, and even more preferably 2 to 4 folds. The elastomeric foam 21 having an expansion ratio of 1.4 folds or more provides particularly good cushioning properties, and an expansion ratio of 6 folds or lower provides particularly good formability and durability. The expansion ratio mentioned above refers to that of the elastomeric foam 21 itself and not that of the magnetic elastic body 20.
Examples of the magnetic powder 22, which should preferably be made of a ferromagnetic material, include known hard magnetic materials such as neodymium magnetic powder, samarium magnetic powder, alnico magnetic powder, ferrite magnetic powder, and so on. The magnetic powder 22, in particular, is preferably a neodymium magnetic powder which exhibits a high magnetic strength when permanently magnetized. Particles 23 of the magnetic powder 22 may have a flake, spherical, or needle-like shape, for example. The magnetic powder 22 should preferably have a particle size of 3 to 200 μm, and more preferably 5 to 100 μm. Increasing the particle size of the magnetic powder 22 can raise the surface magnetic flux density of the magnetic elastic body 20. That is, if the magnetic powder 22 is made of surface-treated magnet particles, the ratio of the magnetic component of the magnetic powder 22 can be raised by increasing the particle size of the magnetic powder 22, which in turn can further raise the surface magnetic flux density of the magnetic elastic body 20. The particle size of the magnetic powder 22 should preferably be not more than 200 μm from the points of view of formability and deformability of the magnetic elastic body 20. Here the particle size is measured by a test sieving method in accordance with JIS Z 8815:1994. Magnetic powder 22 having a particle size of 3 μm or more provides a particularly good workability. Magnetic powder 22 having a particle size of not more than 200 μm provides a particularly good formability, and prevents possible detachment of the magnetic powder 22 from the elastomeric foam 21 more reliably.
The magnetic elastic body 20 should preferably contain a magnetic powder 22 made of a hard ferromagnetic material, and have a mass concentration (mass percentage) of magnetic powder 22 of 40 to 80% relative to the elastomeric foam 21, and a volume concentration (volume percentage) of magnetic powder 22 of 1.0 to 3.5% relative to the elastomeric foam 21. Such a composition allows for easy elastic deformation of the magnetic elastic body 20 and larger changes in magnetic flux density of the magnetic elastic body 20. The magnetic elastic body 20 should preferably have a compression set of not more than 30% as measured by Method A of JIS K 6262:2013. Moreover, the magnetic elastic body 20 should preferably have a repeated compression set of not more than 20% when compressed by 50% 100,000 times at 1 Hz. Elastomeric foam 21 of such a composition exhibits favorable recovery after undergoing elastic deformation. This enables use of the elastomeric foam 21 with less plastic deformation even in applications where the magnetic elastic body 20 is repeatedly compressed, which is more preferable for repeated use of magnetic elastic body 20.
Next, a method for producing the magnetic elastic body 20 will be described with reference to
Next, the liquid mixture is injected into a mold that is temperature regulated in advance to be expanded and cured into a molded foam of a columnar shape, for example (S13). The magnetic powder 22 is dispersed in the elastomeric foam 21 of this molded foam. In this molded foam, the magnetic moments of individual particles 23 of the magnetic powder 22 are oriented randomly. In the expansion and cure process of the liquid mixture in the mold mentioned above, the liquid is cured for a predetermined time (primary cure) with the mold closed, after which the resultant molded foam is taken out of the mold. The primary cure is performed at 60 to 120° C., for example, for 10 to 120 minutes. The molded foam taken out of the mold after the primary cure should preferably further undergo a secondary cure, which is performed at 90 to 180° C., for example, for 8 to 24 hours. In this embodiment, the elastic member in which the magnetic powder 22 is dispersed is polyurethane elastomer, so that the material takes only a short time to cure, and can be made to cure before the magnetic powder 22 in the material settles. Accordingly it is possible to disperse the magnetic powder 22 evenly. It is thus possible to disperse magnetic powder 22 having a particle size of even 100 μm or more in the magnetic elastic body 20 so that the magnetic flux density of the magnetic elastic body 20 can be made higher. In this embodiment, the magnetic powder 22 is mixed with the second liquid after it has been mixed into the first liquid, so that the magnetic powder 22 can be dispersed evenly in the elastomeric foam 21 as compared to when the magnetic powder 22 is mixed with the first liquid after it has been mixed into the second liquid.
Next, the molded foam described above is magnetized (S14). In this process, the magnetic moments of the particles 23 of the magnetic powder 22 in the molded foam are aligned by applying external magnetic fields. In this embodiment, external magnetic fields are applied in the axial direction of the columnar elastomeric foam 21. Magnetization may be performed to the molded foam in a non-deformed, natural length state, or, in a state axially compressed from a natural length state (e.g. compressed by 50%). The above process produces the magnetic elastic body 20 from the molded foam. It is particularly preferable if the magnetic flux density (surface magnetic flux density) of the magnetic elastic body 20 is increased by 5% or more from that of the natural length state when compressed in the main axial direction by 10%. Such a magnetic elastic body 20 can be produced, for example, by magnetizing the magnetic powder 22 dispersed in the elastomeric foam 21 in a compressed state (e.g., compressed by 50%) in the direction of compression.
The magnetic elastic body 20 of this embodiment can change the magnetic flux density by undergoing deformation (elastic deformation). The electromagnetic induction device 10 of this embodiment can thus generate an induced current I by changing the magnetic flux extending axially through the coil 11 by causing a deformation in the magnetic elastic body 20. This is mainly attributable to some change in magnetization in the magnetic elastic body 20 as described below.
In this embodiment, when the magnetic elastic body 20 is compressed, the air bubbles in the elastomeric foam 21 are collapsed. Therefore, the magnetic elastic body 20 hardly expands in the radial direction of the coil 11 even when it is compressed in the axial direction of the coil 11 (see the change from
It is known that there is the following relationship, along the axial direction of the coil 11, between the magnetic flux density Bz in the magnetic elastic body 20, and the external magnetic field Hz, magnetization Mz of the magnetic elastic body 20, and permeability in vacuum μ0: Bz=μ0·Hz+Mz . . . (A). It is also known that there is the following relationship between magnetization Mz, and the mean value mz of the magnetic moments of particles 23 of magnetic powder 22 in the axial direction of the coil 11 and the number n of particles 23 of magnetic powder 22 per unit volume of the magnetic elastic body 20:
Mz=n·mz (B)
It is considered that compression of the magnetic elastic body 20 in the axial direction of the coil 11 (
In this embodiment, the magnetic elastic body 20 is made of a foam. It is thus easy to increase the distribution density of the particles 23 of the magnetic powder 22 in the magnetic elastic body 20 when the magnetic elastic body 20 is compressed, so that the change in magnetic flux density of the magnetic elastic body 20 can be made larger. This allows the induced current I to be generated easily.
Stretching the magnetic elastic body 20 in the axial direction of the coil, as opposed to the example described above where the magnetic elastic body 20 is compressed, is assumed to cause the magnetization Mz to decrease, and the induced current I will flow in the opposite direction from the case where the magnetic elastic body 20 is compressed.
In the example of
In the electromagnetic induction device 10 of this embodiment, the magnetic elastic body 20 disposed inside the coil 11 is made of an elastomeric foam 21 containing a magnetic powder 22 dispersed therein. As the magnetic elastic body 20 undergoes elastic deformation in the axial direction of the coil 11, an induced current I is generated in the coil 11 (circuit 12). According to this embodiment, as described above, the magnetized body (magnetic elastic body 20) for generating an induced current in the circuit 12 has elasticity, so that the magnetic elastic body 20 is hardly breakable when a force is applied to the magnetic elastic body 20 such as vibration. The elasticity also allows the magnetic elastic body 20 to undergo vibratory deformation when generating the induced current I. Moreover, since the magnetic elastic body 20 is compressed to generate an induced current I in the coil 11, the electromagnetic induction device 10 can be made more compact in the axial direction of the coil 11 as compared to when a rigid body is used instead of the magnetic elastic body 20. Furthermore, according to this embodiment, the magnetic elastic body 20 is made of a foam, and the magnetic elastic body 20 hardly expands in the radial direction of the coil 11 when compressed in the axial direction of the coil 11, so that the electromagnetic induction device 10 can be made more compact also in the radial direction of the coil 11.
Confirmatory Test
It was confirmed that an induced current I was generated in the coil 11 by elastic deformation of the magnetic elastic body 20 disposed inside the coil 11 in the electromagnetic induction device 10. Specifically, generation of an electromotive force in the coil 11, as a substitute value of induced current I, was confirmed.
Configuration of Electromagnetic Induction Device
For the coil 11, a copper coil having a winding diameter (inner diameter) of 36 mm (36Φ), an axial length of 70 mm, a wire diameter of 0.5 mm, a number of windings of 1395, and a resistance of 13Ω was used. For the magnetic elastic body 20, one made of a polyurethane elastomeric foam 21 containing a neodymium magnetic powder dispersed therein was used. Neodymium magnetic powders having different particle sizes (5 μm and 100 μm) were used. The magnetic elastic body 20 is columnar, with a diameter of 23 mm and an axial length of 23 mm. The magnetic elastic body 20 was magnetized with 8 tesla for 3 seconds. The magnetic elastic body 20 was magnetized both in a natural length state and in a state in which the elastic body was compressed by 50% in the axial direction. In this test, the magnetic elastic body 20 was disposed coaxially with the coil 11, and such that the center position in the natural length state of the magnetic elastic body 20 coincided with that of the coil 11. The magnetic elastic body 20 was entirely accommodated inside the coil 11, with its axis oriented in the up and down direction. The magnetic elastic body 20 was elastically deformed by being compressed from one axial end (from below).
Particulars of the magnetic elastic bodies of test examples
The particulars of the materials for the magnetic elastic bodies 20 are as follows:
First Liquid
Polyol; Polyester polyol (Molecular weight: 2000, Number of functional groups: 2, Hydroxyl value: 56 mgKOH/g, Product Name: “Polylite OD-X-102”, produced by DIC corporation
Isocyanate; 1.5-Naphthalene-1.5-diisocyanate (NCO %: 40%, Product Name: “Cosmonate ND”, produced by Mitsui Chemicals Inc.
Neodymium magnetic powder; (1) MQFP (5 μm), produced by Magnequench International, LLC, (2) MQFP (100 μm), produced by Magnequench International, LLC
Second Liquid
Catalyst; Amine catalyst, Product Name: “Addocat PP”, produced by Rhein Chemie Japan
Foaming agent; Liquid mixture containing castor oil and water, Product Number: “Addovate SV” (castor oil/water weight ratio 50:50), produced by Rhein Chemie Japan
This test used magnetic elastic bodies 20 of various expansion ratios of elastomeric foam 21, and various composition ratios, particle sizes, and magnetization methods of the neodymium magnetic powder (Test Examples 1 to 5). The magnetization conditions, and various characteristics of the magnetic elastic bodies 20 of respective test examples are as indicated in
Test Method
Density and Expansion Ratio of Elastomeric Foam
Columnar test samples of magnetic elastic bodies 20 with a diameter of 23 mm and an axial length (thickness) of 23 mm were prepared from the first liquid and second liquid that did not contain neodymium magnetic powder, and the density was measured in accordance with JIS K6268:1998. The expansion ratio of the elastomeric foam 21 was calculated from this density.
Mass Percentage and Volume Percentage of Neodymium Magnetic Powder
The mass percentage of the neodymium magnetic powder was determined by measuring the mass of the neodymium magnetic powder relative to the mass of the first liquid using a weighing scale. The volume percentage of the neodymium magnetic powder was calculated by the following formula from the mass percentage of the neodymium magnetic powder, density of the neodymium magnetic powder, and density of the elastomeric foam 21. The density of the neodymium magnetic powder was 7.6 g/cm3.
Volume percentage of neodymium magnetic powder (%)=(Mass percentage of neodymium magnetic powder×Density of elastomeric foam)/(Density of neodymium magnetic powder).
Compression Set
Test samples of magnetic elastic bodies 20 with a diameter of 13 mm and a thickness of 6.3 mm were prepared, and the compression set was measured in accordance with Method A of JIS K 6262:2013 (Small test piece, 70° C.×22 hours, compressed by 25%).
Repeated Compression Set
Test samples of magnetic elastic bodies 20 with a diameter of 23 mm and an axial length (thickness) of 23 mm were compressed by 50% relative to the natural length state (original thickness) in the axial direction 100,000 times at 1 Hz (once per second), and the rate of change in thickness after this repeated compression test was measured. The repeated compression set was then calculated from the following formula. The measurement was made at normal temperature (23° C.).
Repeated compression set (%)=(Thickness before compression test−Thickness after compression test)/(Thickness before compression test)×100.
Surface Magnetic Flux Density
Test samples of magnetic elastic bodies 20 with a diameter of 23 mm and an axial length (thickness) of 23 mm were prepared. The surface magnetic flux density was determined by measuring the magnetic flux density at the center of both axial end faces, upper face and lower face, 10 times each (20 times in total) using a gauss meter (“MG-601” produced by Magna Co., Ltd.), and by calculating the mean value. The surface magnetic flux density of the magnetic elastic bodies 20 was measured in the natural length state, and in compressed states in which the elastic body was compressed by 10%, 25%, and 50% from the natural length state in the axial direction, and the rate of change in surface magnetic flux density of each compressed state relative to the natural length state was calculated.
Generated Power
The magnetic elastic body 20 was vibrated to undergo deformation such as to be repeatedly compressed and restored in the axial direction of the coil 11 by a test machine 40 illustrated in
The details of the test machine 40 are as follows. The test machine 40 has a piston 41 and a fixing member 42 that hold both ends of the magnetic elastic body 20 in the axial direction of the coil 11 inside the coil 11. The piston 41 vibrates in the axial direction of the coil 11 by the power from a drive source 43 to deform the magnetic elastic body 20 in a vibratory manner. The distance between the fixing member 42 and the piston 41 is set such that it is equal to the natural length of the magnetic elastic body 20 when the piston 41 is farthest from the fixing member 42 in its vibration stroke. Namely, in this test, the fixing member 42 and the piston 41 are always in contact with the magnetic elastic body 20.
Both ends of the coil 11 are connected to an oscilloscope 44, which indicates the electromotive force induced in the coil 11. The test machine 40 further includes a laser displacement sensor 45 for detecting the vibration of the piston 41. The laser displacement sensor 45 outputs signals relating to the amplitude and frequency of the piston 41 to the oscilloscope 44 via an amplifier unit 46 so that the amplitude and frequency of the vibration of the piston 41 can be checked with the oscilloscope 44.
Test Results
Since all the test examples 1 to 5 use polyurethane elastomer for the elastomeric foam 21, they showed favorable results of the compression set of 21 to 25% and repeated compression set of 13 to 18%.
The surface magnetic flux densities in the natural length state of Test Examples 1 to 3 were 9.2 mT, 4.6 mT, and 10.3 mT, respectively, i.e., the larger the volume percentage of neodymium magnetic powder, the higher the surface magnetic flux density. The surface magnetic flux densities in the natural length state of Test Examples 3 and 5 were 10.3 mT and 14.6 mT, respectively, which indicates that the larger the particle size of neodymium magnetic powder, the higher the surface magnetic flux density. The surface magnetic flux densities in the natural length state of Test Examples 3 and 4 were 10.3 mT and 9.2 mT, respectively, i.e., Test Example 3 had a higher surface magnetic flux density. On the other hand, the surface magnetic flux densities in the 10%, 25%, and 50% compressed states were 10.5 mT and 9.9 mT, 10.7 mT and 10.6 mT, and 10.9 mT and 12.6 mT, respectively, and the rates of change were 1.9% and 7.6%, 3.9% and 15.2%, and 5.8% and 37.0%, respectively. That is, in the 50% compressed state, Test Example 4 had a higher surface magnetic flux density. This is attributable to the increase in distribution density of neodymium magnetic powder, as well as the alignment of the magnetic moments of neodymium magnetic powder when compressed as compared to the natural length state. Namely, the number n of neodymium magnetic powder particles per unit volume and the mean value mz of the magnetic moments in the relational equation (B) given above were both increased so that the magnetization Mz was increased, resulting in the larger rate of change in comparison to that of the natural length state. The increased magnetization Mz resulted in the higher magnetic flux density Bz (see the relational equation (A)). The rate of change in surface magnetic flux density from the natural length state when compressed by 50% in Test Example 3 was 5.8%, whereas the rate of change from the natural length state when compressed by 10% in Test Example 4 was 7.6%. This indicates that the change in surface magnetic flux density (magnetic flux density) can be made larger even though the degree of elastic deformation is low.
A comparison between Test Example 1 and Test Example 3 shows that more power was generated when the mass percentage (volume percentage) of neodymium magnetic powder was higher. It is also shown that more power was generated when the compression rate (displacement) was larger and when the frequency was higher.
Examples of Apparatuses Having Magnetic Elastic Body and Electromagnetic Induction Device
As illustrated in
The vehicle 60 is provided with a bump stop 66 that is tubular or annular and fitted to the piston rod 64. When the shock absorber 62 contracts, the bump stop 66 is pressed by the cylinder 65 and compressed between the cylinder 65 and the vehicle body 60B. In the example of this embodiment, the bump stop 66 is cylindrical and includes annular grooves at several positions along the axial direction on the outer circumferential surface. Alternatively, the piston rod 64 may be provided with a flange on the side facing the vehicle body 60B so that the bump stop 66 is compressed between this flange and the cylinder 65. The cylinder 65 and the vehicle body 60B or the flange mentioned above in this example correspond to “a pair of opposing members” in the claims. The shock absorber 62 corresponds to “an extension and contraction mechanism” in the claims.
In the power generation system 50 of this example, a winding (in the example of this embodiment, the coil 11) provided in the circuit 12 is disposed coaxially with the bump stop 66 such as to surround the bump stop 66 inside the suspension spring 63 (see
In the detection device 70 of this example, some of the plurality of cushioning members 78 include the coil 11 of the circuit 12 wound therearound. The cushioning members 78 wound around with the coil 11 are made of the magnetic elastic body 20. Accordingly, when a load is applied to the floor panel 73 and the magnetic elastic body 20 deforms, an induced current I is generated in the coil (circuit 12).
As illustrated in
As described above, when a load is applied to the floor panel 73 causing the magnetic elastic body 20 to deform and an induced current I flows in the coil 11, the detection device 70 of this example determines whether or not this induced current I is within a predetermined reference range. If the induced current falls out of the reference range, the alarm device 75 generates an alarm. Thus abnormality such as an excessive load or abnormal vibration occurring in the floor panel 73 is easily detected. The magnetic elastic body 20 having elasticity allows the cushioning members provided to the floor structure 71 to be used for detection of an abnormality.
Other Embodiments(1) The electromagnetic induction device 10 may be provided to a detection device 80 illustrated in
(2) As long as the magnetic elastic body 20 is disposed inside the coil 11 in the radical direction of the coil 11 in the electromagnetic induction device 10, the magnetic elastic body may be disposed outside the coil 11 in the axial direction of the coil 11. For example, the magnetic elastic body 20 may be disposed such that it is partly accommodated in the coil 11 in its natural length state, while entirely getting out of the coil 11 when compressed.
(3) While the magnetic elastic body 20 is magnetized in the axial direction of the coil 11 in the embodiment described above, the direction of magnetization may be inclined relative to the axial direction of the coil 11.
(4) While the magnetic elastic body 20 in the embodiment described above is columnar, the shape is not limited to this and may be rectangular or spherical. The magnetic elastic body may also be in a product shape of the bump stop 66 described above (see
(5) While the coil 11 and the magnetic elastic body 20 are disposed coaxially in the embodiment described above, they may be disposed such that the center axes of the coil 11 and the magnetic elastic body 20 are parallel, or inclined to each other.
(6) As opposed to the embodiment described above in which the coil 11 is provided to the circuit 12 for generating an induced current, the coil 11 may not necessarily be provided. In this case, the circuit 12 may be disposed such that a current is induced by an elastic deformation of the magnetic elastic body 20.
(7) The elastic deformation of the magnetic elastic body 20 for generating an induced current in the coil 11 (circuit 12), which is compression in the embodiment described above, may be extension, torsion, or flexion.
(8) The magnetic elastic body 20 is made of an elastomeric foam containing a magnetic powder dispersed therein, so that it can readily be cut into any desired shape. Any pieces cut from the magnetic elastic body are magnets themselves having a north pole and a south pole, which may allow application of the magnetic elastic body 20 as toys. Since the magnetic elastic body 20 is lighter than ferrite magnets and the like, it can be used in floating applications in which they are kept floating by a magnetic force of other magnets or the like.
(9) Instead of 1.5-Naphthalene-1.5-diisocyanate (NDI) used as the isocyanate material of the magnetic elastic body 20 in the embodiment described above, methylene diphenyl diisocyanate (MDI) may also be used.
(10) The detection device 80 in the embodiment described above is configured to detect a change based on an induced electromotive force (induced current) in the coil 11 (circuit 12). Instead, the device may be configured to detect a change in the magnetic flux density of the magnetic elastic body 20 with a magnetic sensor. Examples of magnetic sensors include Hall sensors, TMR (tunnel magnetoresistance effect) sensors, GMR (giant magnetoresistance effect) sensors, AMR (anisotropic magnetoresistance effect) sensors, and so on.
Claims
1. An elastic body comprising an elastic member containing a magnetized magnetic powder dispersed therein, the elastic body generating an induced current in a circuit by undergoing elastic deformation to cause a change in magnetic flux density, the elastic member being an elastomeric foam; wherein the elastomeric foam has an expansion ratio of 1.4 to 6 folds and at least includes a part with a continuous air bubble structure.
2. The elastic body according to claim 1, wherein the elastic deformation involves a change in distribution density of the magnetic powder in the elastic body, which causes a change in magnetic flux density.
3. The elastic body according to claim 1, wherein the elastomeric foam is a polyurethane elastomer, and the magnetic powder has a particle size of 3 to 200 μm.
4. The elastic body according to claim 1, wherein
- the magnetic powder is made of a hard ferromagnetic material,
- the elastic body having a mass percentage of the magnetic powder of 40 to 80% relative to the elastomeric foam, and
- a volume percentage of the magnetic powder of 1.0 to 3.5% relative to the elastomeric foam.
5. The elastic body according to claim 1, wherein the elastic body has a compression set of not more than 30% as measured by Method A of JIS K 6262:2013.
6. The elastic body according to claim 1, wherein the elastic body has a repeated compression set of not more than 20% when repeatedly compressed by 50% 100,000 times at 1 Hz.
7. A bump stop made of the elastic body according to claim 1 and wound around with an electromagnetic induction coil.
8. An electromagnetic induction device comprising
- the elastic body according to claim 1, and
- an electromagnetic induction circuit in which a change in magnetic flux density occurring with an elastic deformation of the elastic body causes an induced current to flow.
9. A power generation system comprising
- the electromagnetic induction device according to claim 8, and
- an extension and contraction mechanism for repeatedly extending and contracting the elastic body.
10. The power generation system according to claim 9, wherein the elastic body is formed in an annular or a tubular shape and fitted to a piston rod of a shock absorber of a vehicle, the extension and contraction mechanism including a pair of opposing members provided either to the piston rod and a cylinder of the shock absorber, or to one of the piston rod and the cylinder and a support part that supports the shock absorber, for compressing the elastic body.
11. A detection device comprising the electromagnetic induction device according to claim 8, and a detection circuit that detects a physical change involving a movement in a movable member that compresses, or stretches, or twists the elastic body, based on an induced electromotive force in the electromagnetic induction device.
12. A production method for an elastic body for producing the elastic body according to claim 1, comprising dispersing the magnetic powder in the elastic member, and magnetizing the magnetic powder, in a state in which the elastic member is compressed, in a direction of compression.
13. An elastic body comprising
- an elastic member containing a magnetized magnetic powder dispersed therein, the elastic body generating an induced current in a circuit by undergoing elastic deformation to cause a change in magnetic flux density, the elastic member being an elastomeric foam; and
- a pair of magnetic flux passing parts where a magnetic flux passes through on an outer surface thereof oriented oppositely from each other, wherein compressing the elastic body in a main axial direction along which the pair of magnetic flux passing parts are aligned increases the magnetic flux density.
14. The elastic body according to claim 13, wherein the elastomeric foam has an expansion ratio of 1.4 to 6 folds and at least includes a part with a continuous air bubble structure.
15. An elastic body comprising
- an elastic member containing a magnetized magnetic powder dispersed therein, the elastic body generating an induced current in a circuit by undergoing elastic deformation to cause a change in magnetic flux density, the elastic member being an elastomeric foam; and
- a pair of magnetic flux passing parts where a magnetic flux passes through on an outer surface thereof oriented oppositely from each other, wherein compressing the elastic body in a main axial direction along which the pair of magnetic flux passing parts are aligned increases the magnetic flux density; wherein, when the elastic body is compressed by 10% in the main axial direction from the natural length state, the magnetic flux density increases by 5% or more from that of the natural length state.
16. An elastic body comprising
- an elastic member containing a magnetized magnetic powder dispersed therein, the elastic body generating an induced current in a circuit by undergoing elastic deformation to cause a change in magnetic flux density, the elastic member being an elastomeric foam; and
- a pair of magnetic flux passing parts where a magnetic flux passes through on an outer surface thereof oriented oppositely from each other, wherein compressing the elastic body in a main axial direction along which the pair of magnetic flux passing parts are aligned increases the magnetic flux density; wherein, when compressed in the main axial direction, magnetic moments of the magnetic powder are aligned more in the main axial direction than in a natural length state without any deformation.
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20180202873 | July 19, 2018 | Bonifas |
3051758 | September 1998 | JP |
2002-320369 | October 2002 | JP |
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2019-022435 | February 2019 | JP |
Type: Grant
Filed: Oct 16, 2020
Date of Patent: Nov 1, 2022
Patent Publication Number: 20210125758
Assignees: INOAC CORPORATION (Nagoya), NAGOYA INSTITUTE OF TECHNOLOGY (Nagoya)
Inventors: Nobuyuki Makihara (Okazaki), Yasushi Ido (Nagoya), Yuhiro Iwamoto (Gifu)
Primary Examiner: Jeffrey D Washville
Application Number: 17/072,203
International Classification: H01F 1/06 (20060101); H01F 7/06 (20060101); C08J 9/00 (20060101); C08K 3/08 (20060101); C08J 9/30 (20060101);